This works:

    void vla_print(int n)
    {
      int foo[n];
      printf("Got %zu bytes right there!\n", sizeof foo);
    }

    int main(void)
    {
       vla_print(47);
       return 0;
    }

Even if you "hide" n from the compiler, i.e. make its value something that is only known at run-time (which is jumping through hoops, pretty sure the above is enough).

Also, it was jarring that the fine article kept referring to sizeof as sizeof(), a notation that C programmers typically use to identify function names. As everyone knows, sizeof is not a function. It's an operator. I really need to print up that t-shirt soon. Or maybe my first tattoo ... Hm.

[1]: https://ideone.com/kKf3bT

so what, an array has a size that sizeof can measure. what is returned from malloc is not an array and what sizeof measures is not reflective of the size of the allocation